Adsorption of ry 125 dye from aqueous solution on a silver doped tio2 modified clinoptilolite
1 Politehnica University of Timisoara, Faculty of Industrial Chemistry and Environmental Engineering,
2 Victoriei Sq., 300006 Timisoara, Romania 2Department of Condensed Matter, National Institute of Research-Development for Electrochemistry and Matter Timisoara, 1 Plautius Andronescu, 300224 Timisoara, Romania
2 Victoriei Sq., 300006 Timisoara, Romania 2Department of Condensed Matter, National Institute of Research-Development for Electrochemistry and Matter Timisoara, 1 Plautius Andronescu, 300224 Timisoara, Romania
Abstract
The aim of the present work was to study the dark adsorption of Reactive Yellow 125 (RY 125) using a silver doped TiO2 modified clinoptilolite (Z-TiO2-Ag) envisaging its further application in heterogeneous photocatalytic oxidation. Several kinetic models, i.e., Lagergren, Ho-McKay, Dumwald-Wagner intraparticle models were tested to elucidate some adsorption mechanistic aspects. The pseudo-second order kinetic model proposed by Ho and McKay was the most suitable in describing the adsorption kinetic of RY 125 dye onto Z-TiO2-Ag. The solid-liquid equilibrium experimental data were correlated with four mathematical models, i.e., Langmuir, Freundlich, Dubinin-Radushkevich and Harkin-Jura. The Freundlich isotherm approximated the best the experimental data. A physical nature of adsorption process was found based on the value of the free energy of adsorption, EDR =
Keywords
adsorption; equilibrium; kinetics; reactive dye; silver doped TiO2 modified zeolite